Electronic control circuit for electrohydraulic transducers



Sept. 9, 1969 J. BASSOT ET AL ELECTRONIC CONTROL CIRCUIT FOR ELECTRO-HYDRAULTC TRANSDUCERS Filed Sept. 28, 1967 2 Sheets-Sheer. 1

Sept. 9, 1969 BASSOT ET AL 3,465,730

ELECTRONIC CONTROL CIRCUIT FOR ELECTRO-HYDRAULIC TRANSDUCERS Filed Sept. 28, 1967 2 Sheets-Sheet 2 United States Patent 3,465,730 ELECTRONIC CONTROL CIRCUIT FOR ELECTRO- HYDRAULIC TRANSDUCERS Jacques Bassot, Paris, and Louis Monpetit, Etang-la-Ville, France, assignors to Societe des Procedes Modernes dlnjection Sopromi, Boulogne, France Filed Sept. 28, 1967, Ser. No. 671,502 Claims priority, application9grance, Sept. 29, 1966,

Int..Cl. F0211 1/06, 7/00 US. Cl. 123-32 9 Claims ABSTRACT OF THE DISCLOSURE CROSS-REFERENCE TO RELATED APPLICATIONS This invention relates to electronic control circuits for electro-hydraulic transducers discussed in US. patent application Ser. No. 63 0,035 filed April 11, 1967.

BACKGROUND OF THE INVENTION The subject invention relates to an electronic control circuit for controlling electro-hydraulic transducer means, each of said electro-hydraulic transducer means having one coil, being adapted to open upon energization and close upon deenergization of said coil. More specifically, it relates to the control of injectors in a fuel injectior system.

Systems are already known for internal combustion engines in which the powering of the injectors is controlled by means of power transistors which are in turn controlled by an electronic arrangement as a function of various Operating parameters of the motor.

It is also known that it is possible to recover the energy liberated by the interruption of coil current when the injector is closed, by storing it in a condenser and then reconverting it to magnetic and kinetic energy for opening the subsequent injector.

Such circuits have been proposed in the US. application No. 630,035 of April 11, 1967 in the name of the applicants.

SUMMARY OF THE INVENTION It is the object of this invention to furnish a new solution to this problem. This invention thus constitutes a circuit for controlling the opening and closing of electrohydraulic transducer means in a fuel injection system, each of said electro-hydraulic transducer means having a coil, and being adapted to open upon energization and close upon deenergization of said coil. It comprises a voltage source, and first starting switching means, having a first and second line terminal and a control element, series connected to said coil and adapted to connect said coil to said voltage source upon receipt of an injection start signal at said control element. Further comprised are unidirectional conduction means connected between said first starting switching means and said coil. The circuit also comprises storage means, having a first and second storage terminal, connected to said second line terminal of said first starting switching means at said first storage terminal. It also comprises extinction switching means having an extinction control element, adapted to connect ice said second storage terminal to said voltage source upon receipt of an injection stop" signal at said extinction control element. Finally, second starting switching means having a starting control element are supplied for connecting said second storage terminal to said second coil terminal upon receipt of said injection start signal at said starting control element.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electrical diagram of a control circuit according to this invention;

FIG. 2 is an electrical diagram of a circuit for several injectors;

FIG. 3 is an electrical diagram for the control signal distributing system for the circuit according to this invention;

FIG. 4 is an electrical diagram of the system for controlling the end of the injection.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, there is shown an injector 6, one embodiment of electro-hydraulic transducer means, which, from the electrical point of view, consists of a coil having a coefiicient of self inductance. It is energized by a direct current voltage E between the points 1 and 2. This voltage is generally the battery voltage of the vehicle. In operation, current is supplied to the injector via first starting switching means, here shown as a thyristor 3, unidirectional conduction means, here shown as a diode 4, and finally the resistance 5, all connected in series between the points 1 and 2. Thyristors 7, an extinction switching means, and thyristor 9, a second starting switching means, serve to extinguish the thyristor 3, and also serve to effect the recovery of the magnetic energy contained in the injector coil 6 when energized. This energy is transformed into potential energy stored in the storage means, namely condenser 8. The potential energy in turn will be recoverted into kinetic (or magnetic) energy in the coil of the injector 6 in the next cycle, thus effecting a very rapid opening of the injector.

In order to explain the operation of this circuit, let it first be supposed that the arrangement is started up after a prolonged rest and that consequently the residual voltage on the condenser 8 is zero. First the two thyristors 3 and 9 are fired by a simultaneous application of a signal to the respective gates (control elements) by means of an arrangement which is not shown. The injector 6 is thus energized. The transient current passes through the condenser 8, charging it with the polarity indicated on the top of the condenser 8 in FIG. 1, and also passes through the diode 4 and the resistor 5. After the condenser 8 is fully charged with the polarity shown in the figure, only the steady state excitation current of the injector flows through the diode 4 and the resistance 5, while the thyristor 9 is self extinguished after the capacitor 8 is charged. In order to deenergize the injector, a positive control signal is applied to the gate (extinction control element) of the thyristor 7 by an arrangement which is not shown. Thus the point 10 in FIG. 1 reaches the positive potential, that is to say the potential of the point (1 in FIG. 1, while the point 11, which is the common point joining the thyristor 3, the diode 4 and the capacitor 8), assumes a potential which is higher than the supply potential. This causes the thyristor 3 to extinguish and also causes the closing of an oscillating circuit comprising a capacitor, an inductance and a resistance, namely the capacitor 8, the diode 4, the resistance 5, the injector 6 and the supply battery, by means of the thyristor 7.

At the end of a fraction of an oscillating period, the capacitor 8 is charged to a voltage higher than the supply voltage with the polarity shown at the lower part of the condenser. Therefore the thyristor 7 extinguishes and the injector is no longer activated. However the magnetic energy which was contained in the coil of the injector is recovered in the form of potential energy by the capacitor 8 with small losses in the resistance and the diode 4.

At the time of the following injection, the thyristors 3 and 9 are again fired simultaneously as mentioned above. The diode 4, during the transient time immediately following the firing, is polarized in the reverse direction because of the charge on the capacitor 8 stemming from the energy recovery at the end of the preceding cycle. Injector 6 thus opens very rapidly under the influence of the supply voltage augmented by the voltage corresponding to the charge stored on the capacitor 8. When the latter has discharged sufliciently, diode 4 becomes con ducting, thyristor 9 is extinguished, and the condenser 8 is recharged with the polarity indicated at the top of the condenser 8 and the injector again is energized in a steady manner via the diode 4 and the resistance 5 This completes one full cycle and the equipment is ready for the next cycle.

Obviously this arrangement may be adapted for a plurality of injectors which may be controlled simultaneously if they are connected in series or in parallel, or independently from one another if they are connected in par allel and separated by switches or thyristors.

FIG. 2 shows an embodiment having three injectors controlled independently from one another. The system is again fed by a supply voltage, in general the supply voltage of the vehicle, between the points 21 and 22. The injectors are represented by the coils 36, 37 and 38. It is obvious that this embodiment may be extended to any number of injectors or electro-hydraulic transducers. The operation is analogous to the operation which was described relative to the system shown in FIG. 1 except that to fire a given injector, as for example the injector 36, it is necessary to fire not only the thyristors 23 and 29 by applying a signal to their gates as above, but also at the same time to fire the thyristor 41 which corresponds to the injector 36. Analogously to the operation described above, the firing of the thyristor 27 causes the end of the injection by successively extinguishing the different thyristors. Thyristor 29 is self-extinguished after a quarter of a period of the oscillating circuit comprising condenser 28 and coil 36 (or 37 or 38) at the time of the opening of the injector.

For the following injection, if for example the next injector is to be the injector 37, one again activates the thyristors 23 and 29 simultaneously but this time the thyristor 42 is activated rather than the thyrisor 41. The remainder of the operation is the same. To summarize one may thus say that the arrangement comprising the thyristor 23, 29, and 27, the diode 24, the resistance 25, and the condenser 28 is a switching system embodied entirely in thyristors and furthermore plays a role in the recovery of energy by means of the capacitor 28. Thyristors 41, 42, 43 etc. simply act as current distributors for the current furnished by the switching system which has thus been described.

FIGS. 3 and 4 show an example of an embodiment of a complete control system for a polycylinder motor.

Although a three injector system is shown in FIGS. 3 and 4 this is not to be considered a limitation, but

purely an example. It is obvious that the number can be extended to any desired number of injectors.

The terminals of the supply battery which are marked 101 and 102 are designated the same in different parts of the FIGS. 3 and 4. While the terminal 101 represents the positive terminal of the battery and the terminal 102 the negative, it is obvious that, for example, as far as the distributor is concerned, the voltage may be reversed. In particular the polarity of the grounded side of the battery has no fundamental importance. For any given set-up it is always possible to find the proper set-up in case the polarity of the vehicle battery is reversed. The system consists essentially of three parts: First a firing and distribution arrangement as shown in FIG. 3, second, a switching arrangement analogous to that described with reference to FIG. 2, and finally a time computing arrangement. The combination of the two latter arrangements are shown in schematic form in FIG. 4. The firing and distribution arrangement may be of any known type connected for example to the cam shaft or to any moving part of the motor with angular rotation.

In FIG. 3 it is shown schematically as switches with elastic membranes 103, 104 and 105. The closing of one of the switches with elastic membranes or, more generally, a signal generated by a distributor mounted on the cam shaft of the motor or on a moving part of said motor, causes a current to flow between the ponits 101 and 102 and thus through common transformer means which are mounted on the toroid 109 and one of the primary means of transformer means mounted on toroids 106, 107 or 108. Closing of any one of the switches with elastic membranes 103, 104 or always causes a pulse to flow in the coils on the toroid 109, which coils have terminals marked 110 and 111, and 112 and 113 respectively. As shown in FIG. 4, these coils are connected between the cathode and the gate of the first and second starting thyristors 131 and of the circuit according to FIG. 2. Therefore it follows that closing one of these switches with elastic membrane 103, 104 or 105 causes the firing of the thyristors 130 and 131 as has been explained above. Furthermore, the transformer means or cores 106, 107 and 108 are energized one after the other depending on which of the switches 103, 104 or 105 is closed. These transformers include the secondary means having terminals marked 114, 115, 116, 117, 118, 119 respectively. As shown in FIG. 4 these secondary means are connected respectively between the cathode and the gate of one of the individual starting switching means, namely thyristors 122, 123 or 124 which control injectors 126, 127 and 128, corresponding respectively to the switches 103, 104 and 105.

It therefore follows that closing one of the switches with elastic membranes provokes the closing of the switching circuit described in FIG. 2 and the firing of the thyristor corresponding to the injector which must open at the moment corresponding to the closing of the particular chosen switch. Therefore the injection starts with the desired cylinder.

As shown in FIG. 4 closing of the switch activates a bistable element represented by the unijunction transistor via the diode 132 and the resistance 133.

An arrangement shown only as a block designated 136 represents an arrangement already described in applicants patent application Ser. No. 630,035 of April 11, 1967. This allows a correction of the injection times as a function of the diverse operating parameters of the motor. The variable resistance 133 is also a function of one or several operating parameters of the motor, as, for example, the pressure in the admission pipe in case of a motor with controlled ignition, opening of the butterfly valve, combination of speed and opening of the valve, and other combinations of parameters either directly or indirectly by means of two dimensional or three dimensional cams. The resistance itself may for example be a function of the speed of rotation of the motor in the case of a diesel motor for which regulation takes place as a function of speed.

Generally speaking the closing of a switch causes, by means of the circuit 132 and 133 the starting of a time generator, namely a charging of the capacitor 134, in such a manner that at the end of a certain time, namely a time equal to the injection time, the capacitor 134 reaches a voltage equal to the peak emitter voltage of the unijunction transistor 135, and the latter fires. Therefore an important current pulse appears in coil 137 connected to the base 1 of the unijunction transistor. The coil 137 is a part of extinction transformer means having a secondary whose terminals are marked 138 and 139. The terminals of this secondary coil are connected between the cathode and the gate of the extinction thyristor 129. It therefore follows that the firing of the unijunction transistor '135 causes the firing of the thyristor 139 and therefore the end of the injection as has been previously mentioned.

For the following injection, the closing of the subsequent switch with elastic membranes causes the firing of the corresponding injector and so forth. The principal advantage of this system is that it contains only semiconductor elements, which are not only silicon but also of the breakdown type (extremely rugged thyristors). Furthermore, it has a certain number of advantages with respect to the rapidity of the energy recovery. It must be understood that care is taken that the time which elapses between the firing of the thyristors 130 and 131 and the firing of the thyristor 129 is not less than a value which corresponds to a fraction of the oscillation period of the circuit formed by 125 and 126 during the transient part of the opening, such that the thyristor 129 is never fired before the extinction of the thyristor 130.

While the invention has been illustrated and described as embodied in a particular switching and distributing circuit, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptions should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A circuit for energizing the actuating coil of an electro-hydraulic transducer comprising:

a capacitor having first and second terminals,

first and second circuit terminals adapted to be connected to a source of voltage,

a normally open first starting switch, having an open state and a closed state, connected between said first terminal of said capacitor and said first circuit terminal, said first starting switch having a first control element adapted to close said first starting switch upon receipt of an injection start signal at said first control element,

unidirectional conduction means connected between said first terminal of said capacitor and a first terminal of the actuating coil of said electro-hydraulic transducer,

said second circuit terminal being connected to the second terminal of said actuating coil,

whereby said first switch, said unidirectional conduction means and said actuating coil are connected in series between said first and second circuit terminals,

a normally open second starting switch, having an open state and a closed state, connected between said sec- 0nd terminal of said capacitor and said first terminal of said actuating coil, said second starting switch having a second control element adapted to close said starting switch upon receipt of the injection start signal at said second control element,

a normally open third extinction switch, having an open state and a closed state, connected between said second terminal of said capacitor and said first circuit terminal, said extinction switch having a third control element adapted to close said extinction switch upon receipt of an extinction signal at said control element,

whereby said extinction switch, said capacitor, said unidirectional conduction means and said coil are connected in series between said first and said second circuit terminals.

2 The energizing circuit of claim 1 further comprising:

a current limiting resistor connected in series with said unidirectional conduction means and said actuating coil.

3. The energizing circuit of claim 1 wherein;

said first switch, said second switch and said third switch are unidirectional conduction devices when in a closed state.

4. The energizing circuit of claim 3 wherein:

said switches are thyristors.

5. The energizing circuti of claim 1 adapted to energize a plurality of actuating coils, each actuating coil being associated with a separate electro-hydraulic transducer, further comprising:

a plurality of individual normally open starting switches, a separate one of said individual starting switches connected in series with separate ones of the actuating coils, each of said plurality of individual starting switches having an individual control element adapted to close the associated individual starting switch upon receipt of an injection start signal at the individual control element.

6. The energizing circuit of claim 5 further comprisdistribution means for sequentially applying an injection start signal to said plurality of individual control elements.

7. The energizing circuit of claim 6 wherein said distribution means comprises:

a plurality of distribution switches adapted to be actuated in the ignition order,

a plurality of distribution transformers, each of said distribution transformers having a primary and a secondary, the primary of separate ones of said distribution transformers being connected in series with separate ones of said distribution switches, the secondary of separate ones of said distribution transformers being connected to separate ones of said control elements of said individual starting switches, and

a common transformer having a primary and a secondary, said common transformer primary being connected to each of said distribution transformer primaries so that current through any one of said distribution transformer primaries will flow through said common transformer primary, said common transformer secondary being connected to said control element of said first starting switch and to said control element of said second starting switch,

whereby the closing of any one of said distribution switches will permit energizing the primary of the associated distribution transformer and the primary of said common transformer thereby energizing the corresponding secondaries and consequently energizing the control elements of said first starting switch, said second starting switch and an associated one of said plurality of individual starting switches.

8. The energizing circuit of claim 1 further comprisa time generator responsive to the closing of said start 7 8 ing switches to generate the extinction signal at the References Cited end of a predetermined injection time period. UNITED STATES PATENTS 9. The injection circuit of claim 8 wherein said time 2 815 009 12/1957 Pribble ganeratf-r cofnpnsesi. 3:193:733 7/1965 Orsino 317-1485 3 5 3,242,352 3/1966 Long 307-252 XR means for firing said uni unction transistor at the end 3,338,221 8/1967 Schenof said predetermined injection time period, and 3,391,306 7 /1968 Piccione 317 151 extinction transformer means responsive to the firing of said unijunction transistor to generate the extinction LAURENCE GOODRIDGE, Pnmary Examlnel' signal and to apply the extinction signal to saidcon- 10 US. Cl. X.R. V trol element of said extinction switch. 123119, 140 

